SSI assurance maladie - not sure what to do next.

I while ago I asked the question about transferring my assurance maladie to the SSI as my french small business is now becoming my main activity. You suggested I contact CPAM as they are taking over independents and I may not have to move Caisse anyway. I duly did contact my CPAM but they simply told me to contact the SSI. I contacted the SSI by their webform and got an automated reply saying I would be contacted and no need to follow up with a letter. That was over a month ago and I’ve heard nothing. Not sure what to do next. I’ve booked an RDV with my local SSI office in St Brieuc but not sure if this is the right thing to do or if I should contact Harmonie Mutuelle, who was the Caisse I picked when I first registered as a business?... I would like to get this sorted as currently I’m not being reimbursed for my regular medications. Whilst this isn’t a large amount of money, I would like to be back in the system properly.. I think I’ve also read that CPAM are taking over all independents from next year? Also whilst writing, my Pacse partner was covered by my UK S1 whilst we had them but is now without cover. I believe he will need to apply under PUMA as Ayant Droit is being phased out?.. (he’s an early retiree drawing a pension).